This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our goal is to investigate new drug therapies for endometriosis. Macaque endometrium can be auto-transplanted to ectopic intra-abdominal and subcutaneous sites. These endometrial grafts provide an excellent endometriosis-like model system for preclinical testing of novel anti-endometriotic therapies. Mineralocorticoid receptor (MR) has been identified as a potential new target for treatment of endometriosis in women. However, most anti-MR compounds cross react with the androgen receptor (AR) and progesterone receptor (PR). The Specific Aim in this study was to compare the effects Spironolactone (anti-MR;anti-PR;anti-AR) with Eplerenone (an anti-MR with no known affinity for AR), Casodex, (a pure anti-AR) and ZK 099 (a pure anti-PR) on estrogen action on ectopic endometrium in rhesus macaques.